Download Cardiovascular System Notes

SECTION 2: A Closer look at Blood Vessels
Blood vessels
=Carry blood to all tissues in body.
-All blood vessels end-to-end would be 62,000 miles long
Arteries
= Carries blood away from the heart.
-The right ventricle pumps blood into the arteries that go to the lungs.
-The left ventricle pumps blood into the aorta.
-Coronary arteries carry blood to the heart itself.
Artery Structure
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The walls of arteries are generally very thick.
Artery walls consist of three cell layers.
-The innermost layer, which is made up of epithelial cells, is smooth.
This smooth surface enables blood to flow freely.
-The middle layer consists mostly of muscle tissue.
-The outer wall is made up of flexible connective tissue.
-Because of this layered structure, arteries have both strength and flexibility.
-Arteries are able to withstand the enormous pressure of blood as it is pumped by the heart and to expand and relax between heart
beats.
Capillaries
=Exchanges nutrients and waste products with the body’s cells.
-Capillary walls are 1 cell thick
-Nutrients and wastes are exchanged are exchanged through a process called diffusion
-Diffusion is movement of substances from an area of higher
concentration to an area of lower concentration
Veins
=Carry blood back to the heart.
-Vein walls are 3 layers thick but much thinner than artery walls
How does blood get back to the heart?
1. contraction of skeletal muscles
2. valves in veins prevent backward flow
3. breathing movements squeeze veins
Blood Pressure
=The force that blood exerts on the walls of blood vessels
-Caused by the force of ventricles
-Measured by sphygmomanometer
Blood Pressure (BP) =
average BP = 120
80
Contraction pressure
Relaxation pressure